On-demand variable flow closed loop gas generator system with a variable area injector

ABSTRACT

A closed loop monopropellant on-demand fuel feeding system for firing a reaction control device. The system includes a single bellows variable area injector having no valves other than an explosive disc in the propellant supply system separating the gas generator from the fuel storage tanks. The injector comprises a stationary pintle with swirl slots and a movable orifice plate attached to the bellows to vary the area of the swirl slots.

nite States Patent Kretschmer et al.

[ 1 Apr. 10, 1973 [5 ON-DEMAND VARIABLE FLOW 3,234,731 2/1966 Dermody etal. ..60/39.74 A

CLOSED LOOP GAS GENERATOR s SYSTEM WITH A VARIABLE AREA agee 3,462,9508/1969 Che a1 ..60/39.74A INJECTOR v a2 75 Inventors: Willi K.Kretschmer, Santa Cruz; Primary Examirwrcarlwn Cwyle Paul Heady, JrMount Herman, Assistant Examiner-Warren Olsen both of Calif Att0rneyR.S. Sciascia et al.

[73] Assignee: The United States of America as [57] ABSTRACT representedby the Secretary of the Navy A closed loop monopropellant on-demand fuelfeeding system for firing a reaction control device The system Flledi g-1971 includes a single bellows variable area injector having [211 App.No; 173 510 no valves other than an explosive disc in the propel- Y lantsupply system separating the gas generator from the fuel storage tanks.The injector comprises a sta- [52] US. Cl. ..60/39.74 A, 60/39.82 E,60/229, tionary pintle with swirl slots and a movable orifice 60/258plate attached to the bellows to vary the area of the [51] Int. Cl..F02k 9/02 swirl slots. [58] Field of Search ..60/39.74 A, 258, 60/229,243, 200, 39.48, 39.82 E

[56] References Cited 10 Claims, 9 Drawing Figures UNITED STATES PATENTS3,527,056 9/1970 Hofi'rnan ..60/258 'r r TP I I -i 59- 5 .1 A\ & a Alllllll nzlus\\: \\\\\\o\" v PATENTEDAPRI 01973 SHEET 2 OF 4PATENTEDAPR] 0 I973 SHEET [1F 4 FIG 6B (IN-DEMAND VARIABLE FLOW CLOSEDLOOP GAS GENERATOR SYSTEM WITH A VARIABLE AREA INJECTOR BACKGROUND OFTHE INVENTION l. Field of the Invention The invention relates generallyto an on-demand variable flow gas generator system and more particularlyto a monopropellent on-demand closed loop fuel feeding system with avariable area injector for firing a reactor control system.

2. Description of the Prior Art The previous systems, to vary the flow,were based on using several injector valves which required a complicatedcontrol system. Moreover, the previous systems, to vary the flow,required additional injectors with the capability of switching theinjectors on or off in order to maintain enough injector differentialpressure (A P) for atomization.

SUMMARY OF THE INVENTION The present invention overcomes theaforementioned problems by reducing the number of valves and injectorswhile maintaining continuous flow through the injectors. Moreover, theunique system is simple, fully automatic, and can be used in anypropulsion device with monopropellent or bipropellent systems. Briefly,the present invention includes a single bellows variable area injectorhaving no valves other than an explosive disc in the propellent supplysystem separating the gas generator from the fuel storage tanks.

The variable area injector is of theswirl type where the propellant isbrought into rotation in orifice plate by slots located in a stationarypintle. The variation in flow is obtained by using the orifice plate tocover and uncover a series of slots in the pintle and thereby change theeffective entrance area to the swirl chamber to match the varying exitarea of the cone and orifice. Movement of a slotted sleeve, which isjoined to the bellows, is initiated by a pressure differential acrossthe bellows and swirl chamber from the decrease or increase in chamberpressure.

An alternative embodiment involves a more complicated open loop systemincluding a two-position fixed area injector which works on theprinciple that for each thrust step, which is initiated by operating gasvalves, a propellent valve is required to match the flow demand tomaintain a constant pressure and continuous flow. The subject matter ofthe aforementioned invention is disclosed in copending U.S. Pat.application Ser. No. 173,508 by W. K. Kretschmer and P. A. Heady, Jr.

STATEMENT OF THE OBJECTS OF THE INVENTION A primary object of thepresent invention is to provide a closed loop two-propellent systemutilizing a variable area injector which maintains continuous flow.

Another object of the present invention is to provide a simple, fullyautomatic, closed loop propellent system which is capable of being usedwith any monopropellent or bipropellent liquid propellent device.

Another object of the present invention is to provide a system withvariable fuel propellent flow to a gas generator at a closed loop systemwhich will maintain a constant combustion chamber pressure at flowvariations of about ten to one.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of the inventionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an assembly drawing of theon-demand gas generator system of the present invention;

FIG. 2 is a drawing of the gas generator of FIG. 1 wherein thrustervalves are used in place of the warm gas valves of FIG. 1;

FIG. 3 is an illustration of the unique solid igniter used in the systemshown in FIGS. 1 and 2;

FIG. 4 is an illustration of the unique warm gas valve used in the gasgenerator of FIG. 1;

FIG. 5 is a schematic drawing of the closed loop system of which the gasgenerators of FIGS. 1 and 2 are a part;

FIG. 6 is an illustration of the unique variable area single bellowsinjector used in the gas generators shown in FIGS.1, 2, and 5;

FIG. 6A is an illustration of the unique pintle cone and orifice plateof injector of FIG. 6;

FIG. 6B is an illustration of the swirl slots of the injector of FIG. 6;and

FIG. 6C is an illustration of sleeve dash'pot of the injector of FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT There are two somewhat similaron-demand gas generators, namely, the closed loop system shown in FIG. 5and the open loop system, not shown, but disclosed in the aforementionedcopending application. Both systems have good response to change in flowdemand for simulation of thrust pulses of different duration and energyat relatively constant chamber pressure (P,). FIG. 1 shows the generalscheme of the on-demand gas generator used in the open and closed loopsystems. The closed loop system shown in FIG. 5, which is the subjectmatter of the present invention, is simple and requires few components.

The variable area injector, illustrated in FIG. 6, combines a flowregulation valve and spring-loaded bellows into one integrated unit.Flow changes in the injector are initiated by chamber pressure Idecrease or increase through changes in gas flow demand by chamberpressure P decrease or increase through changes in gas flow demand byswitching gas valves on or off. The pressure drop across the injectorfor different flow rates varies within a relatively narrow band and theP pressure changes are equal to this A P variation. A more detaileddescription of the unique closed loop system of FIG. 5 and the injectorof FIG. 6 are set forth below.

In contrast, the open loop system with a dual twoposition injector,described in the aforementioned copending application, works on theprinciple that for each thrust step, which is initiated by operating gasvalves, a propellent valve is required to match the flow demand tomaintain constant P pressure. The twoposition injectors of the open loopsystem reduce the number of valves required to three and maintaincontinuous flow through the injector at an injector A P of about 35 psi,or above, at the orifice for six thrust steps.

Referring to FIG. 1, the on-demand variable flow closed loop gasgenerator system 1 comprises gas generator 3, injector assembly 5, hotgas valves 11, 13, 15 and 17 and gas nozzles 25, 27, 29 and 31. Theclosed loop system also includes an igniter 2 which is illustrated inFIG. 2 and described in conjunction with FIG. 3. The volume of the gasgenerator is a function of the characteristic length of the chamber andthe throat or nozzle area. The upper and middle section of chamber 69contains aperature 49 opening onto orifice plate 9 and pintle 7 ofinjector assembly aperature 50 is provided to accept igniter 2, shown inFIGS. 2 and 3. Gas tube openings 51, 53, 55 and 57 are provided toaccept hot gas valves 11, 13, and 17, respectively. The aforementionedhot gas valves may be replaced by a standard thruster cluster ifdesired. The igniter 2 and injector 5 are threaded into valve openings49 and 50, respectively of cylindrical chamber 69. To protect thechamber walls and domes from overheating a silica phenolic insulation orother equivalent material may be used. More specifically, the generatormay be lined with a spiral wound 0.2 inch thick silica phenolic liners.This insures gas flow over the liners in the direction of the spiralwindings and prevents delamination. The generator shown in FIG. 1 can beprovided with gas tube liners 23 to line tube openings 51, 53, 55 and57. impingement liners 25 may be used to line cylindrical chamber 69.Chamber liners 27 can be used to line chamber domes 65 and 67 to preventoverheating of the chamber domes. Nicrome screens 19 including screensupports 21 may be installed into gas generator 3 to filter contaminentsand to prevent nozzle blockage. The screens are respectively mounted inthe ends of domes 65 and 67, adjacent to cylindrical chamber 69 andsupported in the axial direction by the semi-tubular shaped screensupports 21. The screen supports 21 are preferably made of columbium orthe equivalent. Domes 65 and 67 each contain ports 59 and 61 to functionas a gas relief valve or safety valve. Safety disc assembly 41, withextension pipe 39, is attached to port 61 of dome 67. Safety disk 41 canbe ruptured at 2,000 psig and acts as an upper limit gas pressure reliefvalve. Dome idle orifice 45 and extension pipe 37 are attached to port59 of dome 65. The idle orifice takes the place of an idle gas reliefvalve. The idle orifice includes the idle flow nozzle 47 and a 750 psiburst disc 43. The burst disc 43 bursts at ignition and provides abypass flow for exhaust gas at idle flow. Openings are also provided inthe extension pipes 37 and 39 for temperature probes TP.

Referring to FiG. 5, the closed loop system 111 comprises squib 113,fuel expulsion gas generator 115,

' pressurization line 117, Otto Fuel tanks 119 and 121,-

burst disc 123, fuel feed line 125, gas generator igniter 131, Otto Fuelgas generator 129, thruster valves 133 and 135 and variable flowinjector 127. Each of the clusters 133 and 135 contains four thrustervalves, or four warm gas valves, as the case may be, at each end of thechamber of gas generator 129, as illustrated in FIG. 1. Flow changes inthe injector are initiated by a chamber pressure P decrease or increasethrough changes in gas flow demand by switching gas valves on or off.The pressure drop across the injector for different flow rates varieswithin a relatively narrow band; a P pressure is equal to thedifferential pressure variation A P. An ancillary solenoid switch mayalso be used.

Referring to FIG. 2, the gas generator 3 comprises cylindrical chamber69, two dome ends and 67 and thruster cluster 71 and 73. The thrustervalve clusters include thruster valves with thruster nozzles whichattach directly to the domes, 65 and 67, as illustrated in FIG. 2. Asectional view of gas inlet 63 of injector 5 is also illustrated. Thepropellent injector 5 is located in the middle of cylindrical chamber69. It should be noted that the warm gas valves shown in FIG. 1 and 6are used to simulate the above-mentioned thruster cluster shown in FIG.2. A description of the warm gas valves shown in FIG. 6 will follow.

The ignition of Otto Fuel can be accomplished by an electric preheateror with solid igniter. The latter device is more desirable becauseignition must be instantaneous. In FIG. 3 is illustrated the solidigniter 2 used in the system shown in FIGS. 1 and 2. Solid igniter 2comprises filter 79, foil discs 81 and 91, nozzle 83, burst disc 87 andstand pipe 89. Propellent grain is located in the inner upper body ofigniter 2. Ball powder 85 circumferentially surrounds burst disc 87 andstand pipe 89. To obtain a rapid gas generator pressure rise from solidigniter 2, smokeless powder is used as a booster because it has a highburning rate and is a good gas producer. To maintain the pressure level,the non-perforated external burning cylindrical propellent grain 75 issimultaneously ignited with the powder 85 which continues to burn forabout 0.4 seconds. The igniter 2 consists of two chambers 2a and 2bwhich are internally separated by foil rupture disc 81. The frontchamber 2a contains the igniter nozzle 83 with filter 79. Igniterassembly 2 is threaded into aperature 50 of gas generator 3 in the planeof injector 5 and tilted at an angle of 30 to the axis of the injector5. The rear chamber 2b contains a burst disc 87 and a stand pipe 89which prevents the loss of powder 85 into gas generator 3 before burningand during ignition.

The ignition may be completed by an igniter squib 77 or a similardevice. The propellent grain 75 is preferably nonperforated, or holelessgrain, to provide a longer burning time. It has been found byexperimentation that by eliminating the hole in the grain, the grainburning time increased by 3 A times, or from 0.15 to 0.4 seconds, using20 grams including about 0.5 grams of boron potassium nitrate (BKNO Anormal charge of ball powder would be between 6 and 12 grams for goodresults. The rupture disc 87 is set to burst at about 750 psig with apeak pressure in the gas generator of about 770 psig at 0.4 second witha grain burnout at 0.4 second.

To simulate the on-demand condition in the Otto Fuel gas generator, atotal of four warm gas valves are required. Referring to FIG. 4, each ofthe gas valves 1 1, 13, 15 and 17 comprises a water cooling manifold 93,

bellows 95, poppet head 97, seat insert liners 99, 101,

103 and 105, and nozzle 107. Each valve has a sealed pneumatic valvebellows with an operational gas temperature of about 1,500 F at 1,500psig pressure. The gas valves simulate the function of theaforementioned thruster cluster. However, the warm gas valves may beused as the thruster valves in certain types of vehicles using reactioncontrol devices such as target drones. All gas passages are lined withcolumbium material and the valve seat and poppet units are also made ofcolumbium material. A provision for water cooling is desirable in theoperative system. Each valve is fitted with a nozzle 107 that isinstalled downstream of the gas valves. The warm gas valve openingsequence can be calculated and established in a standard manner. Theactivation may be by gas generator pressure or an ancillary solenoidvalve. The discussion of the valves is informational only and not thesubject matter of the present invention.

Referring to FIGS. 6, 6A, 6B and 6C, the unique variable area injector139 is a swirl type and comprises stationary pintle 141, attaching nut143, O ring seal 145, top plate 147, sleeve 149, dash pot 151, metal 0ring 159, bellows flange 161, housing 163, bellows 165, orifice plate167, swirl slots 183, and fuel flow paths 179. The propellant is broughtinto rotation in orifice plate 167 by means of tangential swirl slots183 in the stationary pintle 141. At the exit of the injector 139 aconical sheet of fuel develops having fine atomized droplets. Thevariation of flow in the design is obtained by moving orifice plate 167which uncovers a series of swirl slots 183 in pintle 141 and changes theeffective exit area of swirl slots 183. Movement of the orifice plate167, which is joined to bellows 165 is initiated by the pressuredifferential A P across the bellows 165, sleeve 149 and swirl chamber185. The flange 150 of injector sleeve 149, shown in FIG. 6C, is apiston which is connected to dash pot seal 151. The flange 150 of sleeve149, which is attached to orifice plate 167, is free to move verticallywithin the limits of flange limiting area 187. The pintle 141 includes adownward extending portion 181 and cone 141k which forms a swirl chamber185. The downward extending portion 181 includes eight swirl slots 183.Each slot forms a 45 angle to a line tangent to the exterior section.The pintle point, or cone, 141b extends, when bellows 165 is in theexpanded position, so that the attached orifice 167 and the pintle pointMlb form a line parallel to the base of the orifice 167 when in theclosed position. The top of the pintle 141 has a hollow section 161a toallow the fuel to flow when burst disc 123, shown in FIG. 5, isfractured. The fuel flows through side ports 173 of pintle lel along apath through sleeve 149 ports 175 and between bellows 165 to the swirlslots 183. Sleeve 149 includes three small pressure balancing holes 153,155 and 157 located on sleeve flange 150, as shown in FIG. 6C. Thesleeve 149 includes upper ports 175 which align with pintle ports 173and lower ports 177 which align with swirl slots 183 and to form acontinuous fuel flow path direct to swirl chamber 185. When bellows 165is extended so that swirl slots 183 are open, the fuel flows throughswirl slots 183 to swirl chamber 185 and into the orifice aperature 171that opens onto gas generator 3. The inner vertical walls of the bellows165 and the vertical walls of the sleeve 149 form the flow path for thefuel. The sleeve 149 is also ported at the top and bottom, thus forminga path for fuel flow, as mentioned above. The orifice plate 167 includesa bored orifice section 171 allowing fuel to exit into generator 3. Theorifice plate further includes a circular slotted or recessed portion169 to accept the downward extending portion 181 of the pintle 141 andto act as a closure means to control the amount of swirled fuel from theswirl slots 183 exiting into the gas generator 3. The total effectiveflow area is a function of the slots and orifice plate exit areas. Thecone angle of the pintle is designed to bring the pintle diameter andthe hole of the swirl plate into an even position, as described above. Asmall movement of the swirl plate, about 0.007 inch from this point, isenough to develop a cone spray of approximately 54 at the desired lowflow of 0.09 lb/sec of Otto Fuel with an injector A P of 23 psi. Dashpot seal 151 is incorporated into the design to help eliminate excessivepressure oscillation during idle flow. The seals 151 may be made ofTeflon or other similar material. The fixed pintle 141 is fastened totop plate 147 by nut 143. The injector housing 163 is attached to topplate 147 and is separated slightly by metal 0 ring 159. The pintle cone141b and the downward extending section 181, when openly aligned withsleeve ports 177, form a flow path 179 to swirl chamber 185. The pintle141 is fixed wherein the bellows 165 is operatively coupled to theorifice plate 167. The sleeve 149 is attached to orifice plate at recesssection 169 so that when bellows 165 compresses or expands, the orificeplate 167 and sleeve 149 move correspondingly and in phase with bellows165.

The overall system functions in the following manner with approximatetiming sequences being determined by experimentation, as illustrated inTable I.

TABLE I Time (seconds): 0 Ignition of solid igniter squib 0.016 Power tosolenoid of propellant value 0.16 Arrival and ignition of Otto Fuel ingas generator 0.180 Rupture of burst disc 0.40 Solid igniter burstReferring to FIG. 1, burst disc 123, located between fuel feed line andOtto Fuel tanks 119 and 121, bursts at ignition. The idle orifice 45takes the place of a gas relief valve for idle operation.

Referring to FIG. 6, the flange of sleeve 149 has three holes 153, 155,and 157 drilled to allow for the exchange of Otto Fuel between the upperand lower side of the flange 150. The holes are each 0.0135 inches indiameter. The system then functions as a dash pot when coupled with adash pot seal 151 to damp out excessive pressure oscillations duringidle flow. Holes 153, 155 and 157 allow the necessary pressureequalization. The system has stable operation with rapid flow changes upto 7.25/1 and the capability of handling flow variation of 13/1 withchanges in the spring constant of the bellows and the injector valvestroke. Moreover, increases to 20/ l for idle periods are possible byadding a fixed flow pilot hole to the injector. The system requires novalves other than an explosively operated burster disc 123 in thepropellant supply line 125 to separate the gas generator and thepropellant tank during storage. The fuel system is selfregulating andresponds almost instantaneously to changes in chamber pressure P fromidle to demand flow. This type of unique injector can also be used withother monopropellants such as hydrazine and MHF as well asbipropellants. The gas generator may be constructed of titanium or othersimilar lightweight high temperature material that is well known in theart.

What is claimed is:

7 flow means, variable flow injector, igniter and a gas generator with aplurality of thruster means, said injector comprising in combination:

a. a fuel inlet operatively connected to said fuel flow means;

b. fuel discharge ports;

0. a stationary pintle device including said fuel inlet and saiddischarge port and a cone shaped point attached to a circular shapeddownward extending portion, said downward extending portion including ameans for swirling fuel and a plurality fuel discharge slots;

(1. a vertically extending partially enclosed sleeve with an upperflange portion and a lower flange portion having swirling fuel exitports said sleeve circularly encompassing said stationary pintle;

e. a bellows portion circularly encompassing said sleeve, saidcircularly surrounding pintle wherein a space between said bellows andsaid sleeve forms a fuel flow path for said fuel;

f. an orifice plate operatively attached to said bellows and said sleeveso that when said'bellows compresses or expands said sleeve and saidplate move in a vertical direction with respect to said bellows;

g. said plate having an orifice opening onto said gas generator; and

h. said sleeve having a recessed portion to accept said downwardextending portion of said pintle wherein said recessed portion variesthe discharge area of said slots.

2. The device in claim 1 wherein said igniter is operatively attached toan opening into said gas generator at a 30 angle from said injector toallow a convergence between ignited fuel and injector fuel at locuspoint in said generator.

3. The device recited in claim 1 wherein said igniter is divided into afirst section and a second section wherein said first and second sectionare separated by a foil burst disc, said first section comprising asolid propellent grain and a squib to ignite said propellant and afilter attached to a nozzle, said nozzle discharging said ignitedpropellant at such a pressure to break said disc, thus allowingpropellant to enter said second section, said second section comprisingball powder surrounding a further burst disc and a foil disc whichseparates said second section from the chamber of said gas generator,said ignited propellant subsequently igniting ball powder and breakingsaid discs, thus allowing said ignited propellant to enter said gasgenerator.

4. The device recited in claim 1 wherein said sleeve includes a pressureequalization means.

5. The device recited in claim 4 wherein said equalization means is aflange extending from the upper portion of said sleeve and said flangeincluding three pressure equalization holes wherein said flange islocated between a vertical limiting means whereby said vertical movementof said flange bellows and orifice plate are limited by said limitingmeans.

6. The device recited in claim 5 wherein said equalization means furtherincludes a sealing means coupled to said flange wherein said flangehaving holes and said sealing means, when located in said limiting meansfuncti nsas dash 7. e device re ited in iaim 1 wherein said swirl slotsare tangentially intermittently located at 45 of the side walls of saiddownward extending portion of said pintle and in a stationaryrelationship with respect to said orifice.

8. The device recited in claim 7 wherein the propellant is brought intorotation into said orifice plate by means of said tangential slots ofdownward section of said stationary pintle in a swirl chamber formed bysaid orifice and said slots.

9. The device recited in claim 8 wherein said movable orifice includes aslotted portion to accept said downward extending portion with saidtangential slots whereby said orifice plate in moving away from saidpintle said tangential slots are uncovered thus varying the efiectivearea of said swirl chamber.

10. The device recited in claim 9 wherein said swirl chamber is joinedto the bellows wherein said movement is initiated by a pressuredifferential across the bellows and swirl chamber wherein the resistanceto movement by said bellows is further controlled by a pressureequalization means.

I I! III

1. An on-demand closed loop variable flow gas generator for a reactioncontrol system including a fuel flow means, variable flow injector,igniter and a gas generator with a plurality of thruster means, saidinjector comprising in combination: a. a fuel inlet operativelyconnected to said fuel flow means; b. fuel discharge ports; c. astationary pintle device including said fuel inlet and said dischargeport and a cone shaped point attached to a circular shaped downwardextending portion, said downward extending portion including a means forswirling fuel and a plurality fuel discharge slots; d. a verticallyextending partially enclosed sleeve with an upper flange portion and alower flange portion having swirling fuel exit ports said sleevecircularly encompassing said stationary pintle; e. a bellows portioncircularly encompassing said sleeve, said circularly surrounding pintlewherein a space between said bellows and said sleeve forms a fuel flowpath for said fuel; f. an orifice plate operatively attached to saidbellows and said sleeve so that when said bellows compresses or expandssaid sleeve and said plate move in a vertical direction with respect tosaid bellows; g. said plate having an orifice opening onto said gasgenerator; and h. said sleeve having a recessed portion to accept saiddownward extending portion of said pintle wherein said recessed portionvaries the discharge area of said slots.
 2. The device in claim 1wherein said igniter is operatively attached to an opening into said gasgenerator at a 30* angle from said injector to allow a convergencebetween ignited fuel and injector fuel at locus point in said generator.3. The device recited in claim 1 wherein said igniter is divided into afirst section and a second section wherein said first and second sectionare separated by a foil burst disc, said first section comprising asolid propellent grain and a squib to ignite said propellant and afilter attached to a nozzle, said nozzle discharging said ignitedpropellant at such a pressure to break said disc, thus allowingpropellant to enter said second section, said second section comprisingball powder surrounding a further burst disc and a foil disc whichseparates said second section from the chamber of said gas generator,said ignited propellant subsequently igniting ball powder and breakingsaid discs, thus allowing said ignited propellant to enter said gasgenerator.
 4. The device recited in claim 1 wherein saiD sleeve includesa pressure equalization means.
 5. The device recited in claim 4 whereinsaid equalization means is a flange extending from the upper portion ofsaid sleeve and said flange including three pressure equalization holeswherein said flange is located between a vertical limiting means wherebysaid vertical movement of said flange bellows and orifice plate arelimited by said limiting means.
 6. The device recited in claim 5 whereinsaid equalization means further includes a sealing means coupled to saidflange wherein said flange having holes and said sealing means, whenlocated in said limiting means, functions as a dash pot.
 7. The devicerecited in claim 1 wherein said swirl slots are tangentiallyintermittently located at 45* of the side walls of said downwardextending portion of said pintle and in a stationary relationship withrespect to said orifice.
 8. The device recited in claim 7 wherein thepropellant is brought into rotation into said orifice plate by means ofsaid tangential slots of downward section of said stationary pintle in aswirl chamber formed by said orifice and said slots.
 9. The devicerecited in claim 8 wherein said movable orifice includes a slottedportion to accept said downward extending portion with said tangentialslots whereby said orifice plate in moving away from said pintle saidtangential slots are uncovered thus varying the effective area of saidswirl chamber.
 10. The device recited in claim 9 wherein said swirlchamber is joined to the bellows wherein said movement is initiated by apressure differential across the bellows and swirl chamber wherein theresistance to movement by said bellows is further controlled by apressure equalization means.